Faults in electrical wiring are a serious concern, especially for the aerospace and aeronautical industries. There are a number of airplane and spacecraft accidents that have occurred as a result of faulty wiring creating shorts or opens, resulting in loss of control of the aircraft or in arcing leading to fires and explosions. TWA flight 800 is one example where an electrical wire failure resulted in the loss of many lives. Wire and cable testing is usually performed on the ground after the crew reports an anomaly encountered in flight, but often such failures appear as the result of vibration and cannot be seen while the aircraft is stationary. Today's testing methods regularly require removing wires or cables to inspect them, which can be expensive and labor intensive. It would be desirable to measure wire performance in situ without removing them. It would also be desirable to detect core wire damage during operation, i.e., on a live wire. It would also be desirable to detect damage before a wire completely fails, e.g., to detect damage to the insulation layer of a wire before the insulation layer is completely cut and exposes the wire core to a short or an open.
Wires are often bundled to connect complex electronics or multiple load devices. Wires in cables or other wire bundles sometimes chafe against each other or otherwise wear the insulation to develop arcs and other types of faults, opens, or shorts. Many of these faults are not detected until a complete failure of one or more devices occurs. It can be labor intensive and difficult to test each wire in a bundle even when damage is known to have occurred, and often not feasible to test for damage before complete failure occurs. Previous methods of detecting damage to wires in bundles often were not able to monitor damage in real time and could not detect intermittent damage or determine the extent of the damage. It would be desirable to detect damage in wire bundles when it first occurs, on live wires, e.g., during a flight in the case of wires on an airplane, and be able to immediately identify the damaged wire. It would also be desirable to be able to take action immediately when damage is detected.